GB 2 112 547 A already discloses a protection apparatus for a machine tool, at least for protecting a workpiece surface against overheating. In said document, the protection apparatus comprises a sensor unit which has at least one sensor element, and comprises an evaluation unit by means of which it is possible to identify a temperature of a workpiece surface of a workpiece which can be machined by means of the machine tool on the basis of at least one characteristic variable which is detected by means of the sensor unit. The sensor element, which is provided for detecting a temperature and is electrically connected to the evaluation unit, is arranged outside a tool, wherein the sensor element is protected, in particular, against being influenced by a fluid flow.